1. Field of the Invention
The present invention relates to metal oxide coating materials that can be used as thin film coatings and lithographically or non-lithographically patternable thin film coatings on various substrate surfaces. Furthermore, the invention concerns materials that can be used for building up various electronic and opto-electronic device structures. The invention also deals with methods of making metal oxide materials.
2. Description of Related Art
As known in the art, organo-modified silicon dioxides can be employed for forming optically transparent and electrically well insulating layers by using them as organo-siloxane polymers, also known as “sol-gel polymers”. For example, in the simplest case, silicon tetraethoxide or silicon tetrachloride is hydrolysed and condensation polymerisation of the hydrolysed monomer results in a siloxane polymer that can be converted to a silicon dioxide material under thermal treatment. Furthermore, organo-siloxanes can be made lithographically patternable by attaching photo-crosslinking moieties covalently to the silicon oxide backbone. A silicon oxide material based on pure silicon dioxide or even organo-modified silicon dioxides exhibit, however, a relatively low refractive index. Refractive indices of these materials are typically around 1.5 and their dielectric constants are in the range from about 4.2 to 2.5 depending on their structure and on the moieties attached to silicon. When silicon is replaced by other elements of the periodic table of elements that have a higher number of electrons, such as germanium, titanium, tin, antimony, tantalum, hafnium or zirconium, much higher refractive indices as well as dielectric constants can be obtained. However, if these metal oxides are hydrolysed and co-condensed from pure metal alkoxide or metal chloride precursors, very unstable material systems are obtained which results in a gel type and fully cross-linked (non-dissolvable) polymer after a while.